Re: Pretty much any operation related to Gluster mounted fs hangs for a while

[Joe Julian <joe@xxxxxxxxxxxxxxxx>]

Nothing but GlusterFS should be writing to bricks. Mount a client and write there.

On 01/26/2015 01:38 PM, Tiago Santos wrote:

Right.

I have Brick1 being constantly written. But I have nothing writing on Brick2. It just get "healed" data from Brick1.

This setup is still not in production, and there's no applications using that data. I have rsyncs constantly updating Brick1 (bring data from production servers), and then Gluster updates Brick2.

Which makes me wonder how may I be creating multiple replicas during a split-brain.

It may be the case that, having a split-brain event, I may be updating versions of the same file on Brick1 (only), and Gluster understands it as different versions and things get confuse?

Anyways, while we talk I'm gonna run Joe's precious procedure on split-brain recovery.

On Mon, Jan 26, 2015 at 7:23 PM, Joe Julian <joe@xxxxxxxxxxxxxxxx> wrote:

Mismatched GFIDs would happen if a file is created on multiple replicas during a split-brain event. The GFID is assigned at file creation.

On 01/26/2015 01:04 PM, A Ghoshal wrote:

Yep, so it is indeed a split-brain caused by a mismatch of the trusted.gfid attribute.

Sadly, I don't know precisely what causes it. -Communication loss might be one of the triggers. I am guessing the files with the problem are dynamic, correct? In our setup (also replica 2), communication is never a problem but we do see this when one of the server takes a reboot. Maybe some obscure and difficult to understand race between background self-heal and the self heal daemon...

In any case, a normal procedure for split brain recovery would work for you if you wish to get you files back in function. It's easy to find on google. I use the instructions on Joe Julian's blog page myself.


  -----Tiago Santos <tiago@xxxxxxxxxxxxxxxxx> wrote: -----

  =======================
  To: A Ghoshal <a.ghoshal@xxxxxxx>
  From: Tiago Santos <tiago@xxxxxxxxxxxxxxxxx>
  Date: 01/27/2015 02:11AM
  Cc: gluster-users <gluster-users@xxxxxxxxxxx>
  Subject: Re: Pretty much any operation related to Gluster mounted fs hangs for a while
  =======================
    Oh, right!

Follow the outputs:


root@web3:/export/images1-1/brick# time getfattr -m . -d -e hex
templates/assets/prod/temporary/13/user_1339200.png
# file: templates/assets/prod/temporary/13/user_1339200.png
trusted.afr.site-images-client-0=0x000000000000000400000000
trusted.afr.site-images-client-1=0x000000020000000900000000
trusted.gfid=0x10e5894c474a4cb1898b71e872cdf527

real 0m0.024s
user 0m0.001s
sys 0m0.001s



root@web4:/export/images2-1/brick# time getfattr -m . -d -e hex
templates/assets/prod/temporary/13/user_1339200.png
# file: templates/assets/prod/temporary/13/user_1339200.png
trusted.afr.site-images-client-0=0x000000000000000000000000
trusted.afr.site-images-client-1=0x000000000000000000000000
trusted.gfid=0xd02f14fcb6724ceba4a330eb606910f3

real 0m0.003s
user 0m0.000s
sys 0m0.006s


Not sure exactly what that means. I'm googling, and would appreciate if you
guys can bring some light.

Thanks!
--
Tiago




On Mon, Jan 26, 2015 at 6:16 PM, A Ghoshal <a.ghoshal@xxxxxxx> wrote:

Actually you ran getfattr on the volume - which is why the requisite
extended attributes never showed up...

Your bricks are mounted elsewhere.
  /exports/images1-1/brick, and exports/images2-1/brick

Btw, what version of Linux do you use? And, are the files you observe the
input/output errors on soft-links?

  -----Tiago Santos <tiago@xxxxxxxxxxxxxxxxx> wrote: -----

  =======================
  To: A Ghoshal <a.ghoshal@xxxxxxx>
  From: Tiago Santos <tiago@xxxxxxxxxxxxxxxxx>
  Date: 01/27/2015 12:20AM
  Cc: gluster-users <gluster-users@xxxxxxxxxxx>
  Subject: Re: Pretty much any operation related to Gluster
mounted fs hangs for a while
  =======================
    Thanks for you input, Anirban.

I ran the commands on both servers, with the following results:


root@web3:/var/www/site-images# time getfattr -m . -d -e hex
templates/assets/prod/temporary/13/user_1339200.png

real 0m34.524s
user 0m0.004s
sys 0m0.000s


root@web4:/var/www/site-images# time getfattr -m . -d -e hex
templates/assets/prod/temporary/13/user_1339200.png
getfattr: templates/assets/prod/temporary/13/user_1339200.png: Input/output
error

real 0m11.315s
user 0m0.001s
sys 0m0.003s
root@web4:/var/www/site-images# ls
templates/assets/prod/temporary/13/user_1339200.png
ls: cannot access templates/assets/prod/temporary/13/user_1339200.png:
Input/output error

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--

Tiago Santos

MustHaveMenus.com

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